Britain might have to use Trident on its enemies unless more is spent on conventional forces, Gavin Williamson warned today.

The Defence Secretary raised the spectre of nuclear war as he demanded more investment in the military.

In chilling comments aimed at Chancellor Philip Hammond, Mr Williamson said funding for defence was about ‘making sure things do not happen’.

He said if the UK did not have an effective army, air force and navy the country might have to ‘turn to the greatest deterrence of them all’.

The Royal United Services Institute Sea Power Conference in London, Mr Williamson said: ‘You do not want to be in a position where your only deterrence against threat and against aggressors is a nuclear deterrence.

‘We have got to talk about deterrence being full-spectrum, right across the board.

‘It is sometimes difficult to explain to people that actually investing in our armed forces is all about making sure that things do not happen.